1. Field of the Invention
The invention relates generally to a method of manufacturing a capacitor in a semiconductor device. More particularly, the invention relates to a method of manufacturing a capacitor in a semiconductor device capable of preventing oxidization of a diffusion prevention film due to oxygen existing in a Ru film during annealing process performed after deposition of a Ta2O5 film, thus improving reliability of the device, in such a way that the Ru film as a lower electrode of the capacitor in which a Ta2O5 film is used as a dielectric film is formed by introducing Ru of a raw material, oxygen and NH3 in order to reduce oxygen or a NH3 plasma process as a subsequent process is performed in order to remove oxygen existing on the surface of the Ru film.
2. Description of the Prior Art
As the integration level of devices becomes higher, in order to secure the capacitance of a capacitor in which a Ta2O5 film is used as a dielectric film, it is required that the thickness of the Ta2O5 film be smaller. However, there is a problem that this causes an increased leakage current. Therefore, in order to solve the problem, there is a method of forming a lower electrode of the capacitor with a metal, thus securing the capacitance. The characteristic of the leakage current could be also improved depending on the film quality of this lower electrode.
The Ru film, that is widely used as the lower electrode, is deposited by using Tri(2,4-octanedionato)ruthenium as a raw material by means of LPCVD method. At this time, oxygen is used as a reaction gas wherein oxygen gas functions to facilitate deposition of Ru since it disrupts the molecular structure of Tri(2,4-octanedionato) ruthenium being a raw material. If oxygen is used as a reaction gas, however, there is a problem that oxygen may exist within the Ru film. Therefore, after deposition of a Ta2O5 film, a TiN film of a diffusion prevention film formed in the bottom is oxidized through annealing process, thus forming a dual capacitor or causing a film lift phenomenon.
It is therefore an object of the present invention to provide a method of manufacturing a capacitor in a semiconductor device capable of preventing oxidization of an underlying diffusion prevention film, by reducing oxygen being a reaction gas for forming a Ru film when the Ru film is used as a lower electrode.
According to a first embodiment of the present invention, a raw material of Ru, and oxygen and NH3 are introduced to dissolve the raw material by means of oxygen within the Ru film and thus to reduce oxygen by means of NH3, so that oxygen does not allowed to exist within the Ru film.
Also, according to a second embodiment of the present invention, a process by which a raw material of Ru, and oxygen and NH3 are introduced to deposit a Ru film in a desired thickness, and a NH3 plasma process is performed to remove oxygen within the Ru film, is implemented by a desired times.
Further, according to a third embodiment of the present invention, a process by which a raw material of Ru, and oxygen and NH3 gases are introduced to dissolve the raw material by means of oxygen, a Ru film is deposited by a desired thickness by reducing oxygen by means of NH3 and a NH3 plasma process is then performed to remove oxygen existing within the Ru film, is implemented by a desired times.
In order to accomplish the above object, a method of manufacturing a capacitor in a semiconductor device according to a first embodiment of the present invention is characterized in that it comprises the steps of mounting a semiconductor substrate in which given structures are formed onto a furnace and then maintaining the furnace at given temperature and pressure; introducing a Ru raw material, oxygen and a NH3 gas into said furnace to form a Ru film on said semiconductor substrate; and forming a lower electrode by patterning said Ru film and then forming a dielectric film and an upper electrode on the entire structure.
Also, a method of manufacturing a capacitor in a semiconductor device according to a second embodiment of the present invention is characterized in that it comprises the steps of mounting a semiconductor substrate in which given structures are formed onto a furnace and then maintaining the furnace at given temperature and pressure; forming a Ru film on said semiconductor substrate by introducing a Ru raw material and oxygen into said furnace and then performing a NH3 plasma process for said Ru film; and forming a lower electrode by patterning said Ru film and then forming a dielectric film and an upper electrode on the entire structure.
Further, a method of manufacturing a capacitor in a semiconductor device according to a third embodiment of the present invention is characterized in that it comprises the steps of mounting a semiconductor substrate in which given structures are formed onto a furnace and then maintaining the furnace at given temperature and pressure; forming a Ru film by introducing a Ru raw material, oxygen and a NH3 gas into said furnace and then performing a NH3 plasma process for said Ru film; and forming a lower electrode by patterning said Ru film and then forming a dielectric film and an upper electrode on the entire structure.